Electron tube rigidizing means



1955 R. R. MACHLETT ET AL ELECTRON TUBE RIGIDIZING MEANS Filed Dec. 6,1950 FIG. I

FIG. 2 1:

INVENTORS RAYMOND R. MACHLETT JOSEPH LEF SON W4.

ATTORNEY Patented. Aug. 2, 1955 2,714,676 ELECTRON TUBE RIGIDIZING MEANSRaymond R; Machlett, New Canaan ,.and Joseph Leferson, Springdale,Conn., assignors to Machlett Laboratories, Incorporated, Springdale,Conn., a corporation of (Torn necticut Application Decemberfi, 19-50,Serial No; 199,438 3 Claims. (Cl. 313-40) This invention. relates tomeans for increasing the rigidity of envelope portions of electrontubes. In particular this invention offersa means of increasing, therigidity of. members; located at one: end of a coaxial electron tube. 1

The development of coaxial electron tube constructions has given, riseto many mechanical as well as electrical problems. Mechanical strengthand rigidity requirements for envelope members often are determined bythe type of handling which tubes must undergo. Where some portion of theenvelope is bent: or flexed, it may impose stresses which cause workhardening and eventual breakage. The tendency for envelope parts to bendin coaxial tubes is most pronounced at the tube ends which arefrequently-not reinforced.

In the past thisbending has presented an especially great problem intube constructions employing a block anode at one end affixed near itsactive surface to a reentrant shell member which forms part of thevacuum envelope. This problem is common because reentrant shellstructures are widely employed as thermal expansion compensationmembers-4. e., they are made of material whose expansion matches that ofthe surrounding adjacent anode terminal. There is an advantage, ofcourse, in making the anode of a highly conducting material such ascopper, in order to conduct the heat away from the active anode surface,but, were this block connected at the tubes base to the anode terminal,the expansion of the block would be greater than that of the terminal.The resulting reduction in inter-electrode spacing would cause amaterial change in the operating frequency. With a reentrant Kovar shellattached to a Kovar anode terminal at the tube base and the shell joinedin turn at its other end to the copper block anode near its activesurface, the problem of frequency shift is minimized, but the problem ofrupture of the envelope due to bending is introduced.

The bending problem frequently arises at the tubes anode end becausecooling fins which are rigidly attached to the anode block are often theonly tube appendage external of the cavity and, hence, a convenienthandle 5 for plugging a tube into or extricating it from a cavity. Inaccomplishing these operations it is difiicult to keep pressure whollyaxial, but failure to do so produces radial pressure which tends to bendsome portion of the envelope to which the anode is attached. Frequentflexing of the envelope in this manner will eventually result in ruptureof thevacuum wall.

Thus it is the primary object of our invention to eliminate theopportunity for members coaxial with one another at the end of anelectron tube to move with respect to one another. Accordingly, a rigid,essentially planar member is forced into contact with the coaxialmembers perpendicular to the axis thereof. The axial force upon thisplanar member prevents the radial displacement of any contacting coaxialmember relative to any other contacting member. It is our object to thusprevent relative radial displacement of tube envelope parts by simplemeans which can be easily and cheaply made. It is. furthermore ourobject that this means be separate from the tube so that it may besalvaged in the event of tube failure.

It is an incidental object of our invention in the common case lnvolvinga tubes anode end, where the anode.

terminal is the tubes largest, to provide a stop means.

for the contacting spring fingers of the cavity. Use of the preferredform of our invention will save the use of more complicated diesrequired for fabricating anode ter minals which incorporate such a stop.

Another incidental object of our invention is to lend rigidity to theterminal member itself. If this member has an edge at one end which isunattached or attached to another rather flexible member, it is possiblethat bend ing or flexing the terminal might. damage the envelopeinsulator. increasing the rigidity of the terminal member.

For a description of our invention reference ismade to the followingdrawings:

Fig. 1 shows the preferred form of our rigidizing means whereon isemployed tubular flange means in a bottom View elevation.

Fig. 2 shows a side elevational view of the same structure.

Fig. 3 shows an elevational view of an electron tube.

whichemploys my rigidizing means in combination. withits coolingstructure.

ig. 4. shows in partial section: the electron tube. and. rigidizingmeans of Fig. 3.

Fig. 5 shows a bottom elevational view of a modified. form of rigidizingmeans whereon a modified flange means is employed.

Fig. 6 shows the same structure in elevation from the side.

Figs. 1 and 2 illustrate the simplest, preferred form of our rigidizingmeans which consists merely of a circular planar member 10 having acentral circular opening therethrough with a tubular flange 11 fixedperpendicularly to the planar member 10. It is usually convenient tomake the planar member 10 of relatively heavy gauge metal or otheressentially rigid, yet somewhat resilient, material. Member 10 need notalways be circular itself nor need the hole at its center always becircular, but some portion of it must always extend radially so that itwill bear against coaxial members at one end of the tube.

Figs. 3 and 4 illustrate how the rigidizing means may be used with acoaxial tube structure to prevent flexing and breaking of the tubeenvelope. The tube shown is a triode of the inverted lighthouse type,but: any coaxial tube having adjacent envelope portions may use thisnovel rigidizing means. In this common case member Iii rests againstanode ring terminal 12 and simultaneously against anode block 13. Itheld securely against terminal 12 and block 13, member 10 will preventbending and flexing of envelope parts, particularly the reentrant shellmember 14 aflixed between the anode block and the tubular terminal 12.It may also prevent the cracking of the glass ring 15 to which terminal12 is sealed. It may be noted in passing that member 10 may be madehaving a radially stepped shape in order to bear against coaxial partsof structures at diiferent axial levels, but such modification isobviously inconvenient. The anode block is normally hollow, in part toaccommodate the exhaust tubulation 16. This hollow is commonly enlargedto accept the tubular support 17 of cooling fins 18. As shown here, thistube appendage may be aflixed by threaded engagement with the anodeblock or it may be affixed thereto by any other conventional means. Thetubular support passes through the central opening of the rigidizingmeans so that the flange portion 11 of this means rests in its finalposition atop the fins 18. As is shown Our invention prevents such anoccurrence by- Y a "it here, an extra heavy fin 18a may be used toincrease its rigidity since it is the member supplying axial pressurethrough flange 11 to the rigidizing means. Of course, when the coolingfins are not relied upon for the needed axial pressure upon therigidizing means any other tube appendage or fixture may be relied uponfor the same purpose.

Figs. 5 and 6 illustrate one change that is possible in the rigidizingmeans. Tubular flange 11 is here modified to a series of short radialflanges 11 perpendicular to the planar member 10'. Other modificationsin the shape of flanges are possible as are modifications in the shapeof the central opening and in the overall shape of the planar member 10.

It is, of course, possible to use our rigidizing means, with suitableinsulation, where necessary, between any coaxial members of the tubeenvelope. In some instances it may even be possible that some portion ofthe tube envelope itself may pass through the central opening of therigidizing means, thus simplifying the type of appendage necessary toexert the needed axial pressure.

All modifications in shape and use as suggested above or in the claimsare intended to be within the scope and spirit of our invention.

We claim:

1. Means in addition to an electron tube envelope for increasing therigidity and preventing the relative radial movement of members of theanode assembly of said electron tube, which members are coaxial andradially separated from one another, comprising a circular planaressentially rigid member which has a central circular opening through itthrough which connecting means between the anode assembly and coolingmeans may pass, one side of which planar member bears against coaxial,radially spaced portions of the anode assembly and the anode terminaland the other side of which member has a plurality of radially extendingflange members arranged in a circle surrounding the central circularopening.

2. An electrode assembly comprising a hollow tubular electrode andsupporting means therefor, connecting means securing together saidelectrode and supporting means and including a housing member and ashell member secured together at one end, the shell member at its otherend being secured to the electrode, and the housing member at its otherend being secured to the supporting means, an annular planar memberbearing against the end of the connecting means and the electrode, andcylindrical means connecting the electrode with and bearing radiallyagainst the planar member.

3. An electrode assembly comprising a hollow tubular electrode andsupporting means therefor, connecting means securing together saidelectrode and supporting means and including a housing member and ashell member secured together at one end, the shell member at its otherend being secured to the electrode,-and the housing member at its otherend being secured to the supporting means, an annular planar memberbearing against the end of the connecting means and the electrode,tubular flange means on the inner periphery of the annular planarmember, and cylindrical means connected to the eelctrode andextendingthrough and bearing radially against said tubular flange means.

References Cited in the file of this patent UNITED STATES PATENTS2,367,331 Bondley Jan. 15, l945 2,446,017 McArthur et al July 27, 19482,455,868 Koch Dec. 7, 1948 2,462,921 Taylor Mar. 1, 1949 2,481,026 Lawet al. Sept. 6, 1949

